The fungus, Aspergillus fumigatus causes a wide spectrum of human arid animal disorders such as allergic bronchopulmonary aspergillosis (ABPA), extrinsic allergic alveolitis, aspergilloma and invasive aspergillosis. An invasive form of aspergillosis is becoming increasingly important in immunosuppressed conditions due to environmental pollution, enhanced use of chemotherapeutic drugs and antibiotics etc. The most susceptible hosts are immunocompromised patients, such as cases with organ transplant, leukemia or acquired immunodeficiency syndrome (AIDS).
Currently available tests for identification of this fungus is based on tedious, time consuming, less sensitive methods such as microscopy, cultures, electrophoresis and immunodiffusion. Many clinical features of aspergillosis are similar to tuberculosis and most of the aspergillosis patients are put on antituberculous therapy. The microscopy of the specimen for identification of Aspergillus hyphae is not easy under field conditions and specimens from the patients in the early stages of disease are often negative in the direct mounts. Further, the fungal culture generally takes 3-4 weeks and is expensive as a routine diagnostic measure. The widely used skin testing for Aspergillus allergic patients lacks sensitivity and specificity as the mixture of allergens used for testing is not well characterised and needs standardisation. The steroid therapy used for allergic patients and chemotherapy for invasive patients are more beneficial when employed in the early stages of the disease. Consequent to these factors, many investigators recommend that early diagnosis of aspergillosis should be considered as a priority area of research and development.
Peptides mimicking the epitopes in native antigens have been utilised in diagnosis as well as therapy of hepatitis, influenza, malaria, AIDS etc. Peptides based diagnosis of aspergillosis would be standardised and cost effective. Thus, the focus of research in aspergillosis pertaining to these aspects lies in the identification and purification of diagnostically relevant allergens and antigens of A. fumigatus and identification and synthesis of the epitopic peptides with sequences derived from the diagnostically relevant allergens and antigens.